Tetrachlorinated chromogenic compounds

ABSTRACT

BENZO(A)XANTHENE-12-1&#39;&#39;-PHTHALAN)   WHEREIN EACH R IS HYDROGEN OR AN ALKYL RADICAL HAVING 1 TO 4 CARBON ATOMS.   A CHROMOGENIC MATERIAL OF NORMALLY COLORLESS FORM IS DISCLOSED HAVING THE STRUCTURAL FORMULA:   9-(N(-R)2-),3&#39;&#39;-(O=),4&#39;&#39;,5&#39;&#39;,6&#39;&#39;,7&#39;&#39;-TETRA(CL-)SPIRO(12H-   BENZO(A)XANTHENE-12,1&#39;&#39;-PHTHALAN) OR   4,9-BIS(N(-R)2-),3&#39;&#39;-(O=),4&#39;&#39;,5&#39;&#39;,6&#39;&#39;,7&#39;&#39;-TETRA(CL-)SPIRO(12H-

fl wd. tates Ofice k.

3,654,314 Patented Apic 1972 ABSTRACT OF THE DISCLOSURE A chromogenic material of normally colorless form is disclosed having the structural formula:

4, Cl \O wherein each -R is hydrogen or an alkyl radical having 1 to 4 carbon atoms.

This invention relates to colorless, but colorable fluoran dyes for use in pressure sensitive record material. More specifically, this'invention relates to tetrahalo-fluoran dyes.

Throughout this application, it is to be understood that the fiuoran dyes are substantially colorless until reacted with an acidic material.

Heretofore, some of the pressure sensitive, mark-forming systems of the prior art employed fluoran dyes which are substantially colorless in form when in liquid solution, but which are connected to colored forms upon reactive contact with acidic material. Often, there are problems with the intensity and'hue of these colored forms. For example, color instability on exposure to light frequently occurs.

Colorless, but colorable tetrahalo-fiuoran dyes now have been found. The tetrahalo-fluoran dyes of this invention have improved lightfastness qualities, i.e. improved fade resistance. I I

Pressure sensitive, mark-forming systems of the prior art include a marking system of disposing on or within sheet support material, mutually reactant but unreacted mark-forming components and a liquid solvent in which each of the mark-forming components is soluble. The liquid solvent is present in such form that it is maintained isolated by a pressure rupturable barrier from at least one of the mark-forming components until an application of 2 Claims tetrahalo-fluoran exhibits a blue color not pressure causes a breach or rupture of the barrier in the area delineated by the pressure pattern. The mark-forming components thereby are brought into reactive contact, producing a distinctive mark. i Y

The tetrahalo-fluoran dyes of this invention having chromogenic properties can be incorporated in a web or coated onto the surface of a web to provide a manifolding unit, which is useful in carrying out methods of marking involving reactive contact with color activating material 0 to yield colored reaction products in areas where marking is desired.

The colorless, but colorable tetrahalo-fiuorans of this invention are represented by the formula:

n 01- Z=o o1 wherein each R is hydrogen or an alkyl radical having 1 to 4 carbon atoms. Preferably each R is hydrogen, methyl or ethyl.

The tetrahalo-fluorans of this invention can be produced by any method known in the prior art. Generally, tetrachloro-phthalic anhydride is reacted with a diethylamino phenol to give tetrachloro-benzoic acid. This is then reacted with a phenol or naphthalene in the presence of sulfuric acid to yield the desired fluoran. Prior art processes are described in U.S. Pat. 3,501,331 and Beilsteins Handbuch der Organischem Chemie, copyright 1934 by Julius Springer in Berlin, volume XIX, paged 348-349.

Not only is the fade resistance of these tetrafluorans desirable, but other advantageous properties also are present. For example, the amino-substituted fused ring present in the unhalogenated compound.

A composition of matter is disclosed which comprises a colored product of chemical reaction having a resonant chemical structure and produced by contact of a coloractivating material with one of the above-mentioned chromogenic compounds. The color-developing or activating material is an acidic substance useful for converting the chromogenic compounds to colored forms.

The method of marking of this invention, i.e., the method of developing a colored material from substantially colorless or slightly colored chromogenic compounds, comprises providing a chromo'genic compound selected from among the above-mentioned compounds and b'rin'ging suchchromogenic compound into reactive contacfwith'an'aci'dic color-activating substance, in areas" where marking is desired, tq produce a colored form of the chromogenic compound by the action thereupon of the -acidic substance.-r-'=". c Acidicmaterials employed in this 'invention' can be any coinpound'within the definition of a Lewis acid, i.e. ,'any electron acceptor, Preferably, aCidicorgani'c polymers such as phenolic polymersare employed as the acidic material. The novel chromogenic materials exhibit the advantage of improved color stability when they are reacted with such phenolic polymers. Solution formation of solid particles of the polymeric material in a solvent system with the substantially colorless chromogenic compounds permits penetration of the colored reaction product into a porous support sheet, e.g., paper, so that the colored form of the chromogenic material is absorbed into the body of the sheet and is not merely on the surface of the sheet. The absorption feature provides protection against erasure of recorded data by attrition of the surface of a record sheet.

In a two-sheet unit, the bottom surface of the overlaying sheet is supplied on the surface or near the surface with a multiplicity of minute pressure-rupturable microcapsules containing a solution of the substantially colorless, chromogenic component. An acidic component, such as an acid clay or a phenolic polymeric material lies Within the lower web or undersheet or upon the upper surface of the lower web or undersheet. A colored mark is made by the use of a stylus, a type character, or other pressureexerting means applied to the two-sheet unit manifold.

The encapsulated solution is released on the event of rupture of the capsules in writing operations. The released solution is transferred from the overlying or base-sheet to the receiving surface of the underlying sheet in conformance with the pressure pattern of the writing operation. The top of the underlying sheet is coated or impregnated with a material reactant with the chromogenic material, e.g., an acid clay or an acidic phenolic polymer material; and capsules are present on the overlying or base-sheet which capsules contain a liquid solution of chromogenic material. In another embodiment of the record material, the capsules can contain the polymeric phenolic material in liquid solution and the receiving surface of the underlying sheet can be supplied with the chromogenic material.

It is possible to incorporate the chromogenic material in a solid, crystalline state in a binder material so that the chromogenic material can be transferred from the overlying sheet, upon the application of pressure, to deposit some of the chromogenic material on the receiving surface of the undersheet, which receiving surface carries a color-activating polymeric material. Preferably, the chromogenic substance is dissolved in an appropriate solvent and minute droplets of the solution of the chromogenic material are encapsulated in minute, rupturable, capsules. It is apparent that many other arrangements are possible, including different configurations and relationships of the solvent and all of the mark-forming materials with respect to their. encapsulation and location on the supporting underlying or overlying sheets or web's can be envisioned. Such arrangements are thoroughly described in application for Letters Patent N 0. 392,404, filed Aug; 27, 1964, inthenames of Robert E. Miller and Paul S."Phillips,"Jr.,.-now abandoned. r

The polymeric mark-forming components have a common solubility Withthe novel chromogenic materialv in at least oneliquid solvent when the acid-reactingmaterial reaction with the chromogenic materlals.

is aphenolic orother acidic organic polymer'rln asingle system, several chromogenic:material's can be used-with the same or different polymericmaterials. Severalpolymeric' materials can be reactively. contacted with asingle chromogenic compound or with a mixture of chromogenic compounds. Y

' The solvent can' be maintained inphysical isolation in minute droplets until such time as it is released by appli- "cation' of "pressure. This may'be accomplishedby several known techniques, but, preferably, isolation is maintained by encapsulation of individual droplets of the solvent in a microcapsule according to the procedures described, for exampl e, in U.S, Pan-No; 2,712,507, issued July 5, 1955 on the application of Barrett K. Green; 2,730,457, issued Jan l0, 1956'0n the appliaction of Barrett K. Green andLowell'Schleicher; 2,800,457, issued July 23, 1957 on the application of Barrett K.' Green and Lowell Schleicher;,-2,800,458, issued July 23, 1957 on the application of Barrett K. Green, re-issuedas Reissue Pat. No. 24,899 on Nov. 29, 1960; and 3,041,289,. issued June 26, 1962 on the application of Bernard Katchen and Robert E. Miller. The microscopic capsules, when disposed within or upon a supporting web as a multiplicity in contiguous juxtaposition, are rupturable by .pressure, such as normal marking pressure found, for-example, in writing or, typing operations. l

The material or materials chosen as the Wall material for the droplet-containing microcapsules, in addition to being pressure rupturable,are inert or unreactive with respect to the intended contents of the capsules and the other mark-forming components so that the capsule Wall material remains intact under normal storage conditions until such time as it is released by an application of marking pressure. Preferred examples of eligible capsule wall materials include gelatin, gum arabic and many others thoroughly described in the aforementioned patents.

For most uses in record material, the capsules size does exceed about 50 microns in diameter. Preferably, the capsules are smaller than about 15 microns in diameter.

The acidic organic polymeric material useful for developing the color of novel chromogenic compounds in this invention include phenolic polymers, phenol acetylene polymers, maleic acid-rosin resins, partially or wholly hydrolyzed styrene-maleic. anhydride copolymers and ethylene-maleic anhydride copolymers, carboxy polymethylene and Wholly or partially. hydrolyzed vinylmethylether-maleic anhydride copolymer and mixtures thereof.

More specifically, phenol polymers found useful include alkyl-phenol acetylene resins, which are soluble in common organic solvents and possess permanent fusibility in the absence of being treated by cross-linking materials. Another specific group of useful phenolic polymers are members of the type commonly referred to as novolacs, (a type of phenolformaldehyde polymeric material) which are characterized by solubility in common organic solvents and which are, in the absence of cross-linking agents, permanently fusible. Resol resins, if they are still soluble, can be used, though they are subject, to change in properties upon aging. Generally,-phenolic polymer material found usefuul in practicing this invention is characterized by the pressure of hydroxyl groups and by the absence of groups such as methylol, which tend to promote infusibility orcross-linking of the polymenfiand, further, by being soluble in organic solvents and relatively insoluble in aqueous media. Mixtures ofthese organic polymersand other acidic materials can be employed.

A laboratory method useful in the selection of suitable phenolic resins is the determination of the infrared absorption pattern. It has been found that phenolic resins which undergo absorption in the 3200-3500 cm. region (which is indicative of hydroxyl groups) on the resin molecules and which do not absorb in the 1600 1700cm region are eligible. This latter absorption region is indicative of desensitization of hydroxyl groups whichrlesensitization renders-such groups unavailable for The-preparationaof someorganic polymeric materials useful for practicingithis invention has been described in -Industrialand: Engineering Chemistry, volume 43, pages l34z to l4l, January 1951, and a particular polymer 7 thereof is described in Example I of US. Pat. No. 2,052,

093"; issued to Herbert 'Honel on Aug. -25,-'l936. The

preparation of the phenol acetylene polymers has been described in Industrial and Engineering Chemistry, volume 41, pages 73 to 77, January 1949. The preparation of maleic anhydride copolymers is described in the literature, such as, for example, one of the maleic anhydride vinyl copolymers, as ldisclosed in Vinyl and Related Polymers, by CalvinE. Schildknecht, second printing, published April "1959, by John Wiley & Sons, Incorporated: see pages 65 to 68 (styrene-maleic anhydride copolymer), 530 to 531 (ethylene-maleic anhydride copolymer), and 62810630 ,(vinylmethylether-maleic anhydride copolymer).

When the acidic material used as a mark-forming com ponent in the present invention is one of the aforementioned organic polymers, the liquid solvent is chosen so as to be capable. of dissolving it. The solvent can be volatile or nonvolatile, and a singleor multiple-component solvent can be used which is wholly or partially volatile. Examples ofvolatile solvents useful in practicing the present invention include toluene, petroleum distillate, perchloroethylene and xylene. Examples of nonvolatile solvents include high-boiling-point petroleum fractions and chlorinatedbiphenyls. Generally, the solvent chosen is capable of dissolving at least about 0.3 percent, by weight, of the chromogenic material, and at least about 3 to percent, by weight, of the acidic polymeric material. However, in the preferred system, the solvent is capable of dissolving an excess of the polymeric material. Further, the solvent does not interfere with the markforming reaction. In someinstances, the presence of the solvent has beenfound to interfere with the mark-forming reactionfordiminish'the intensity of the mark. In these arises the solvent chosen should. be sufiiciently volatile assure its, removal from the reaction site soon after liavingbrdi'ijgh fljthemark-forming components into reactivefconta'ct "so that the mark-forming reaction can p' II ,[ISin ehthelimark-forming reaction requires that an intimate fnixture of the components be brought about through solution of saidcom'ponents, one or more of the r riark forming, components f'ca'nfb'e dissolved in solvent droplets isolatedfby encapsulation, the only requirement beingthatat'least one 'fof the components essential to the mark-forming reaction be maintained isolated until the mark-forming reaction is desired;

111; the usual. case, themark-forming components are hosenas to produce a mark upon application of pres- "sure to"'"a "coated system of sheets at room temperature (20 to 25 degrees Centigrade). However, the present invention also includes a 'system'wherein the solvent component is not liquid at temperatures near room temperature but is liquid and in condition for forming solutions only at elevated temperatures.

The support sheet member on which components of the system are disposed can comprise a single or a dual sheet assembly. In the case where all components are disposed on a single sheet," the record material is referred to as a self-contained? or auto'genous system. Where there is a migrationf-of solvent, with or without the markforming component, from onesheet to another, the record material is referred tofas a' transferf system. (Such a system may also be freferred to an; two-fold system, in that at least two sheetsare required and each sheet includes a component, or components, essential to the mark-forming reaction.) Where an adequate amount of the colored reaction productis produced in liquid or dissolved form on a surface of one sheet, a colored mark can be recorded on a second sheet by transfer of the colored reaction product. p

In a preferred case, where microcapsules are employed, they can be present in Zthe sheet support material either disposed therethroufghout or as'a coating thereon, or

both. The capsuleskan be applied'to the sheet material as a dispersion in the liquid vehicle in which they were manufactured, or, if desired, they can be separated from the vehicle and thereafter dispersed in a solution of the acid-reacting polymeric component (for instance, 30 grams of water and 53 grams of a 1 percent, by weight, aqueous solution of polyvinylmethylether-maleic anhydride) to form a sheet-coating composition in which, because of the inertness of the solution and the capsules, both components retain their identity and physical integrity. When this composition is disposed as a film on the support material and dried, the capsules are held therein subject to release of the contained liquid by rupture of the capsule walls. The latter technique, relying on the inertness of the microcapsule and the dispersing medium of the film-forming mark-forming polymeric component, provides a method for preparing a sensitive record material coating having the capsules interspersed directly in a dry film of the polymeric material as the film is laid down from solution. A further alternative is to disperse one or more mark-forming components, and the chromogenic-material-containing microcapsules in a liquid medium not a solvent for either the mark-forming component or the microcapsules, with the result that all components of the mark-forming system can be disposed on or within the support sheet in the one operation. The

several components can be applied individually. The capsules also can be coated onto a sheet reactive with the capsule-contained solution of chromogenic materials.

The respective amounts of the several components can be varied according to the nature of the materials and the architecture of the record material unit desired or required. Suitable lower amounts include, in the case of the chrornogenic material, about 0.005 to 0.075 pound per ream -(a ream in this application meaning five hundred (500) sheets of '25" X 38" paper totalling 3,300 square feet); in the case of the solvent, about 1 to 3 pounds per ream; and in the case of the polymer, about 0.5 pound per ream. In all instances, the upper limit is primarily a matter of economic consideration.

The slurry of capsules can be applied to a wet web of paper, for example, as it exists on the screen of a Fourdrinier paper machine, so as to penetrate the paper web a distance depending on the freeness of the pulp and the water content of the web at the point of application. The capsules can be placed directly in or on a paper or support sheet. Not only capsule structures, but continuous films which contain a multitude of microscopic, encapsulated, droplets for local release in an area subjected to pressure can be utilized. (See, for example, US. Pat. No. 2,299,694 which issued Oct. 20, 1942, on the application of Barrett K. Green.)

With respect to the acidic organic polymeric component, a solution thereof in an evaporable solvent can be introduced into an amount of water and the resulting mixture can be agitated while the evaporable solvent is blown off by an air blast. This operation leaves an aqueous colloidal dispersion slurry of the polymeric material, which can be applied to finished paper so as to leave a surface residue or the slurry can be applied to a wet Web of paper or at the size-press station of a paper making machine, In another method for making a polymersensitized sheet, the water-insoluble polymer can be ground to a desired or required particle size in a ball mill with water, preferably with a dispersing agent, such as a small quantity of sodium silicate. If a binder material of hydrophilic properties is ground with the polymeric material, the binder itself can act as a dispersant. If desired, an amountof binder material of up to 40 percent, by weight, of the amount of polymeric material can be added to the ball-milled slurry of materials;-such binder materials being of the paper coat- .ing binder class, including, for example, gum arabic,

figuration, for the purpose of preventing bleeding of the print.

Another method for applying the chromogenic or polymeric material individually to a single sheet of paper is by immersing a sheet of paper in 1-10 percent, by weight, solution of the material in an evaporable solvent. This operation is conducted individually for each reactant, because if the other reactant material are present, contact of the reacts results in a premature coloration over the sheet area. A dried sheet with one component then can be coated with a solution of another component, the solvent of which is a non-solvent to the already-supplied component.

The polymeric material can also be dissolved in ink composition vehicles to form a printing ink of colorless character and can be used to spot-print a proposed record-sheet-unit sensitized for recording, in a reactionproduced color in those spot-printed areas, by application of a solution of the chromogenic material. In the case of phenolic polymer, a printing ink can be made of up to 75 percent, by weight, of the phenolic polymeric material in a petroleum-based solvent;the ink being built to a viscosity suitable for printing purposes. The relative amounts of reactive, mark-forming, components to be used in practice of this invention, are those most convenient and economical amounts consistent with adequate, desired or required visibility of the recorded data. The resolution of the recorded data is dependent on, among other things, particle or capsule size, distribution and amount of particles or capsules, liquid solvent migration, chemical reaction efliciency, and other factors, all of which can be optimized empirically by one skilled in the art.

In the color system of this invention the acidic markforming material reacts with the chromogenic material to effect distinctive color formation or color change. In a multi-sheet system in which an acidic organic polymer is employed, other materials to supplement the polymer reactants can be included. For example, kaolin can be added to improve the transfer of the liquid and/or the dissolved materials between the sheets. In addition, other materials such as bentonite, attapulgite, talc, feldspar, halloysite, magnesium trisilicate, silica gel, pyrophyllite, zinc sulfate, calcium sulfate, calcium citrate, calcium phosphate, calcium flouride, barium sulfate and tannic acid can be included,

Various methods known to the prior art and others disclosed in the aforementioned application Ser. No. 392,404 in the names of Miller et al., now abandoned and in U.S. patent application Ser. No. 420,193 in the names of Phillips et al., now U.S. Pat. 3,455,721 can be employed in compositions useful for coating mark-forming materials into supporting sheets. An example of the compositions which can be coated onto the receiving surface of an underlying sheet of a multi-sheet to react with a capsule coating on the underside of an overlying sheet is as follows.

Coating composition: Percent by wt.

Phenolic polymer mixture 17 Paper coating kaolin (white) 57 Calcium carbonate l2 Styrene butadiene latex 4 Ethylated starch 8 Gum arabic 2 Having discolsed, generally, the chromogenic materials of this invention and preferred methods for utilizing the chromogenic materials, in combination with other materials, as reactive components in mark-forming record material; examples now are discolsed further illustrating the chromogenic materials.

was carried out by admixing 9.02"grams'of in ml. of sulfuric acid specific'fgrayitylfifi) and heating at C. for ,45 minutes, Heatingjwas continued at C. for an' additional} lioursfffh'e mixture then was cooled and poured into SQOfgr'a I'is of ice. The pH of the mixture then wasfadjus'ted, to'fapH of 10 to 11 by the addition of 50 percentsodiuni by droxide. The mixture was extracted with three 10.0 1111; portions of benzene. After two washings with 10 percent sodium hydroxide, the mixture was washedwithwatei until neutral. After evaporation to a low yoluniqcryst'ail lization was carried out from petroleum 'ethen'Recrystallization from benzene ether resulted in .a' j1ie 1cl, i f 3'8 weight percent. The crystals exhibited a purplev color on clay and had a melting point of 255-265 C. Analysis wasasfollows: 1 Calculated (percent): C, 60.13; H, 3.42; N, 2'."5 0 Cl, 25.37. Found (percent): C, 60.25; H, 3.46; N,.2 .3 8; Cl, 25.19. A.

' EXAMPLE'I I The synthesis of 7 269-270. Analysis was as follows:

Calculated (percent): C, 58.56; H, 3.51; N, 4.88; Cl,

24.69. Found '(percent): C, 58.68; H, 3.59; N, 4.80; C],

EXAMPLE III The following compounds were encapsulated under identical conditions:

Cl I=0 C1 t. C I

NH: CflHg r Ha 0 and 1/10 at start 1 I110 at end 1 Kaolin Kaolin phenol Clay phenol Clay l I/IO is the intensity of color over the intensity of the background. A value of 100 would indicate a white color. Therefore, the less color present the higher the value.

The percent change of relative intensity for the tetrachlorinated fluoran was only 5 to 6 percent. Note, the percent change of the relative intensity for the unchlorinated fluoran varied from 2.5 to 41 percent. Therefore, the tetrachlorinated fluoran demonstrates improved fade resistance over the unchlorinated flouran.

What is claimed is;

1. A chromogem'c compound represented by the formula:

wherein each R is hydrogen or an alkyl radical having 1 to 4 carbon atoms.

2. A compound according to claim 1 wherein R is hydrogen, methyl or ethyl.

References Cited UNITED STATES PATENTS 3,501,331 3/1970 Kimura et a1 260-343.3

ALEX MAZEL, Primary Examiner A. M. TIGHE, Assistant Examiner US. Cl. X.R. 1l7-36.8, 362 

